Penguins, Seals and Whales

Penguins are flightless birds found in the Southern Hemisphere from the Antarctic to the equator. Of the eighteen species, there are four that live in Antarctica and they account for 85 percent of the region's bird population. The Adelie and emperor breed on the Antarctic shores and are the only two species found in the Ross Sea area. Chinstraps breed on islands around Antarctica and gentoos are found from the Antarctic islands to the sub-Antarctic. Another three species (the King, rockhopper and macaroni) live on the sub-Antarctic islands.


The Penguin Gallery

Adelie
Chinstraps
Emperor
Gentoos
King
Macaroni


Coping with Cold Top

Penguins have to be well adapted to the cold. They have short overlapping feathers (like tiles on a roof) to minimise heat loss. Under the feathers is a layer of down and beneath the skin is a thick layer of fat for extra insulation. Their stocky bodies with small extremities (flippers, feet and head) minimise body surface area over which heat loss can occur. Heat loss from their feet is minimised while they are standing. Their social behaviour also conserves warmth - emperor penguins huddle together in large groups during incubation and chicks of all species often group together in creches.

A bedraggled Adelie chick suffers from cold conditions.


Penguin Food Top

Because ice covers almost all of Antarctica, penguins have to get all their food from the sea where they spend about half their time.
Adelie penguins dive into the sea from small ice floes.

They are able to dive very deeply (emperors can dive to 250 metres) and all are excellent swimmers. The feet and tail act as a rudder and the flippers as propellers. They feed mostly on small fish and krill, each one captured individually. A huge amount of food is consumed by a colony of penguins over the breeding season. The Adelie penguins at Cape Crozier have been studied and it was found the adults make approximately 40 feeding trips while raising their chicks, each time bringing back half a kilogram of food. As there are 175,000 pairs at Cape Crozier about 3500 tonnes of food is brought onto the colony for the chicks! The largest rookery is at Cape Adare which has about quarter of a million pairs.

Adelie penguins can swim very quickly - up to 15 kilometres per hour. This gives them the momentum to leap out of the water onto the shore or ice floes. They can leap up to 2 metres, which is also a useful way to escape from predatory leopard seals.

Other ocean predators are killer whales and on land their main predator is the skua, a bird which takes both eggs and chicks

.


Adelie Penguin (Pygoscelis adeliae) Top

The Adelie is the most numerous penguin in Antarctica. It stands 60-70 cm tall and weighs about 5.5 kg. Males and females look the same and have a black head, neck and back and a white ring around their eyes.

They spend the winter on the edge of the sea ice and come onto land in early spring, sometimes having to walk up to 50 kilometres over the ice to reach their nesting ground. They return to the same colony every year and usually to the same mate. The males arrive first and rebuild the nests. After mating, the female lays two eggs in early November and returns to the sea for 8-15 days while the males incubate the eggs. This means the males fast for about four weeks and lose about half their body weight by the time the females return and take over the incubating duty.

For the rest of the incubation period and after hatching, they take turns to return to the sea to feed for 2-3 days at a time. They bring back fish and krill in their crops which they regurgitate to feed the chicks.


Emperor Penguins (Aptenodytes forsteri) Top

Emperors are the largest of all penguins. They are about one metre tall and weigh approximately 30-40 kilograms. They have a black head, a bluey-grey neck with a bright orange patch near the ears and pale yellow breast fading into white.
Emperors are bigger and chick-rearing takes longer than it does for the smaller Adelies.. Chicks need to be independent by summer when food sources are most plentiful, so the eggs have to be laid early. In autumn (April-May) colonies assemble on the sea ice in sheltered bays. A single egg is laid in May or early June and is incubated by the male for two months over the coldest part of the year. The egg is kept on top of the male's feet covered by a flap of blood-rich skin and feathers to keep it warm in temperatures down to -50°C. The male doesn't eat during this time; it would use too much energy to go back and forth across many kilometres of ice to the sea if incubation duty was shared with the females. Instead they have adapted to these extreme conditions by huddling together in huge groups and using their fat reserves for energy and insulation.

The females return to the colony when the chicks hatch and then both parents take turns crossing the ice to the sea to feed and to bring back food for the chick. By January or early February the chicks lose their downy feathers and, although not fully grown are ready to fend for themselves in the sea. They spend their first two years at sea or on the pack ice.


Seals Top

Four species of these carnivorous mammals live and breed in the Antarctic and are all found in the Ross Sea region. These four are "true" or earless seals, those without flaps on their ears. They are of course well adapted to the cold climate, with their big round bodies, layers of blubber and small extremities.

Seals catch most of their prey under water but spend some time on land or ice floes giving birth, raising their young and basking in the sun. On land they are quite ungainly but in the water they are very graceful and are excellent swimmers.

Much larger numbers of seals are found in the Antarctic compared to the Arctic which reflects the much greater abundance of food in the Southern Ocean.


Crabeater Seal (Lobodon carcinaphagus) Top

Despite its name, the crabeater seal feeds almost exclusively on krill which it strains through its teeth. They are the most numerous of the Antarctic seals and live on the pack ice. They reach up to 2.7 metres long and weigh over 250 kilograms, but little else is known about them.


Weddell Seal (Leptonychotes weddelli) Top

More is known about Weddell seals because they live along the Antarctic coastline. In the winter though they spend a lot of time under the inshore sea ice because it is warmer in the water than in the air. They enlarge holes and cracks in the ice by chewing so they can come up for air and, in summer, to lie on the ice. They are about the same size as crabeaters. In spring groups of pregnant females and a male gather on the ice. A single pup is born which feeds on its mother's rich milk, which is the richest milk of any mammal.

They can dive to 600 metres in search of fish and have specially adapted eyes for underwater vision in low light levels.


Leopard Seal (Hydurunga leptonyx) Top

Like crabeater seals, leopard seals are surface feeders with krill an important part of their diet. They also prey on penguins and other seal species and hunt for fish and squid. Not much is known about their breeding habits. They live mostly on the pack ice.


Ross Seal (Ommatophoca rossi) Top

Ross seals are rarely found anywhere but on floating ice and until 1963 less than 20 Ross seals had ever been seen. Little is known about them but it is now known that they are quite plentiful. They hunt squid and fish at depths below the pack ice.


Whales: Exploitation to Protection Top

The killing of whales was one of the early reasons for venturing into Antarctic waters and claiming territory. In the early 1800s and then for another phase after gun powered harpoons were invented in 1870, whaling ships ventured south. About 1.3 million whales have been taken in Antarctic waters this century. Populations of the right, blue and humpback whales were decimated. It is estimated only about one percent of their original numbers survive. The fin and sei whales were also depleted to about 10-20 percent of their original population level.

The reduction in whale numbers began causing concern and in 1946 the International Whaling Commission (IWC) was established to regulate whaling operators, although this did not prevent continuing degradation of blue and humpback whale numbers or the serious depletion of the fin, sei and sperm whales.

With growing international concern for whales blue and humpback whales were fully protected in 1963.
Quotas for other species were gradually reduced until full protection was given to fin and sei whales in the 1970s. A complete ban on commercial whaling came into effect in 1986, although whaling continued illegally and under the guise of "scientific whaling"..

The long lived, slow breeding whales will take a long time to recover from past whaling pressures. It is thought the right and humpback whales may be recovering at the rate of up to seven percent a year but no increase has been noted in blue and fin whale populations.

A Southern Ocean Whale Sanctuary was declared by the International Whaling Commission in May 1994. The sanctuary extends from Antarctica to 40°S, which includes New Zealand waters south of about Wanganui. About 90 percent of the world's whales live in this region and should now be safe from commercial whaling. Japan, however, is still killing minke whales and hunted in the Ross Sea region in 1995. The minkes are relatively numerous, with an estimated population of about 760 000. The blue whale, on the other hand, numbers only about 450, down from its pre-whaling level of an estimated 250 000.


Whale types and migration Top

The whales do not live in Antarctica all year-round. They are found there in the summer, feeding on krill and other marine resources and in the autumn head north into the warmer waters of the tropics. There they give birth, the calf feeding on its mother's rich milk before migrating back to Antarctic waters.

Fourteen species of cetaceans (the name given to whales, dolphins and porpoises) are found in Antarctica. Of these, twelve are whales. There are two groups, the baleen whales and the toothed whales. Cetaceans are highly intelligent mammals. They communicate with sound which also serves as an echo location system.

Baleen is a huge hairy-edged plate in the whale's mouth which acts as a sieve. The whale sieves out krill, small fish and crustaceans.

Six species of baleen whales are found in Antarctica, including the huge blue whale which is the largest animal that has ever lived. It grows up to 24 metres and can weigh 84 tonnes. Other baleen species are the fin, southern right whale, sei, minke and humpback.

Four species of toothed whales are found in Antarctica. Except for the sperm whale, they are much smaller than the baleen whales and weren't widely hunted. The other species are the southern bottlenose whale, the orca whale and the southern fourtooth whale. They all have teeth and feed on fish and squid. The orcas also take penguins and seals.


Further Reading Top

Antarctica (2nd edition). Readers Digest. 1990.

Explore Antarctica. L. Crossley. Cambridge University Press. 1995.

The World of Penguins. C. Gaskin & N. Peat. Hodder & Stoughton. 1991.

Life in the Freezer. A. Fothergill. BBC Books. 1993.

Emperors of Antarctica. Wild South Video.

Icebird. Wild South Video.

Antarctica: A lonely planet travel survival kit. Jeff Rubin. 1996.